
<div>
  <p>myhomework29 works!</p>
  <h3>注册新用户</h3>
  用户名：<input type="text" [(ngModel)]="uname" (ngModelChange)="doUnameChange()">
  <span [ngClass]="unameClass">{{unameMsg}}</span><br>
  密&emsp;码：<input type="password" [(ngModel)]="upwd">
  <span></span><br>
  <button (click)="doSubmit()">提交</button>
</div>